JPH11227343A - Heat-transfer receiving sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an excellent image printing property, and at the same time, suppress the generation of a curl. by using a supporting body wherein on a paper base-material, a foaming resin layer and a plurality of resin layers for which an upper layer is made a non-foaming resin layer, are extrusion- molded by using dies. SOLUTION: A supporting body for this heat-transfer receiving sheet is constituted in such a manner that on a paper base material, at least one layer of a foaming resin layer, and a plurality of resin layers for which an upper layer is resin a non-foaming resin layer, are extrusion-molded by using dies, and on the resin layer, a receiving layer is provided. These foaming resin layer and the non-foaming resin layer are preferably made a polyolefine resin layer for both, and on the opposite surface of the receiving layer of the receiving sheet, a polyolefine layer is extrusion-molded by using dies. Then, for the resin layers, e.g. for the regulation of brightness, an inorganic fine-grain, an organic fine-grain, a fluorescent brightner or the like are used, and at the same time, when necessary, additives such as an anti-static agent, a heat stabilizer, an antioxidant, an ultraviolet ray absorber, and a light stabilizer are blended.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer receiving sheet. More specifically, the present invention is suitable for a thermal printer, particularly a dye thermal transfer printer, hardly generates curl, has good image quality, can obtain an image similar to a silver halide photograph, and is advantageous in terms of cost. The present invention relates to a receiving sheet (hereinafter, simply referred to as a receiving sheet).

[0002]

2. Description of the Related Art In recent years, a thermal printer, particularly a dye thermal transfer printer capable of printing a clear full-color image, has attracted attention. Dye thermal transfer printers superimpose a receiving layer containing a dye-dyeable resin of a receiving sheet on a dye ink sheet, and apply heat at a required concentration of the dye layer on the receiving layer by heat supplied from a thermal head or the like. To form an image. The ink sheet is composed of three colors of yellow, magenta and cyan, or four colors of black and black. A full-color image is obtained by repeatedly transferring the dyes of each color of the ink sheet to the receiving sheet in order.

In such a printer with a thermal head, a dye-dyeable resin is used as a main component on a sheet such as a uniaxially or biaxially stretched film or a multilayer structure film (synthetic paper) in order to obtain good printed images. In many cases, a receiving sheet having an image receiving layer containing the same is used. Such a sheet has advantages such as uniform thickness, flexibility, and low thermal conductivity as compared with paper made of cellulose fiber, and therefore, a uniform and high-density transfer image can be obtained. There is an advantage.

However, when thermal transfer recording is performed on a receiving sheet using the above-described film or synthetic paper as a sheet-like support, the stretching stress of the film is released by heat, and the film contracts due to heat. The curl (print curl) becomes large, making it difficult to run through the printer, and also has the disadvantage that the commercial value of the obtained print is significantly reduced.

In order to prevent such curling, a laminated structure in which a stretched film of PET or the like having relatively low heat shrinkage or a paper substrate is used as a core material, and the above-mentioned film or synthetic paper is laminated on both surfaces thereof. Support is used. PE
A stretched film such as T has high smoothness, and when used as a core material, it can cope with high speed and high image quality of a printer, which is preferable, but increases the cost.

[0006]

SUMMARY OF THE INVENTION The present invention has excellent printing aptitude, has almost no curl, has good surface gloss, and is low-cost paper base material for various thermal printers. And a thermal transfer receiving sheet using the same.

[0007]

Means for Solving the Problems The present inventors have made intensive studies on a receiving sheet using a paper substrate. As a support of the receiving sheet, a support having a multilayer structure in which a film layer such as a synthetic paper is laminated on both sides of a paper substrate is generally used. As the lamination method, a dry lamination method is generally performed, and as an adhesive used at that time, a polyisocyanate-based, epoxy-based curing agent, or the like is added to a polymer resin component such as a polyether-based or polyester-based resin. What was blended is mentioned. However, when a film layer is laminated on a paper substrate using these adhesives, irregularities based on the fiber shape of the paper substrate surface are also transferred onto the film layer surface, and the irregularities cause the heat of the recording head to be reduced. Since the transmission is non-uniform, white spots and the like occur in the image portion, and a sufficiently clear image quality cannot be obtained.

The present inventors have found that the problem can be solved by forming a resin layer by extruding a foamed resin layer and a non-foamed resin layer on a paper base using a die, and providing a receiving layer thereon. This has led to the present invention.

According to the present invention, there is provided a thermal transfer receiving sheet having a support and a thermal transfer receiving layer, wherein the support comprises at least one layer of a foamed resin layer on a paper base and a non-foamed resin layer as an upper layer. Is formed by extrusion using a die,
A thermal transfer receiving sheet comprising a receiving layer provided on the resin layer. Further, it is preferable that both the foamed resin layer and the non-foamed resin layer of the receiving sheet are polyolefin resin layers. Further, it is preferable that a polyolefin layer is formed by extrusion using a die on the opposite side of the receiving layer of the receiving sheet.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, a plurality of resin layers in which at least one layer of a support is a foamed resin layer on a paper base and an upper layer thereof is a non-foamed resin layer are formed by extrusion using a die. The feature is that it is done. The foamed resin layer may have a plurality of layers, and the foamed resin layer may have a plurality of layers. However, the foamed resin layer always has at least one layer, and the outermost layer that forms the receiving layer is the foamed resin layer. It is a configuration having a layer. The structure of multiple resin layers, a foamed resin layer and a non-foamed resin layer, effectively transfers the thermal energy from the thermal head to the receiving layer, achieves high sensitivity, and improves adhesion with the thermal head via the ribbon. It is possible to obtain an improved print with high image quality.

As the paper substrate, a natural pulp substrate mainly composed of wood pulp is preferably used because it has appropriate heat insulating properties and cushioning properties and is advantageous in terms of cost. Among them, those subjected to calendering for high smoothness are more preferably used, and may have a coating layer containing a pigment as necessary. Specific examples include high quality paper, art paper, coated paper, laminated paper, matte paper, impregnated paper, paperboard, and the like. Base paper whose basis weight is 50 to 250 g / m
² is preferred.

The base paper is made of various conventional paper additives such as a dry paper strength agent (cationized starch, cationized polyacrylamide, etc.), a sizing agent (fatty acid salt, rosin, maleated rosin, cationized sizing agent, Etc.),
Filler (clay, kaolin, titanium, etc.), wet paper strength agent (melamine resin, epoxidized polyamide resin, etc.), fixing agent (aluminum sulfate, cationized starch, etc.), PH
It may contain one or more kinds of regulators (such as sodium hydroxide and sodium carbonate). The base paper is a water-soluble polymer additive,
Sizing agent, inorganic electrolyte, hygroscopic substance, pigment, dye, PH
It may be tab-sized or size-pressed with a treatment liquid containing one or more kinds of regulators and the like.

Examples of the resin used for the resin layer including the foamed resin layer and the non-foamed resin layer include polyolefin resins such as high-density polyethylene, medium-density polyethylene, low-density polyethylene, polypropylene, polybutene and polypentene, polystyrene resins, polyethylene terephthalate and the like. Polyester resin, nylon resin, polyurethane resin and the like. The foamed resin layer and the non-foamed resin layer may be formed of different resins, but it is preferable to use the same type of resin from the viewpoint of improving the adhesion between the layers. Among them, it is most preferable that both the foamed resin layer and the non-foamed resin layer are polyolefin-based resin layers because they have good adhesion to the paper substrate and are relatively inexpensive.

In the resin layer, for example, inorganic fine particles, organic fine particles, a fluorescent whitening agent and the like are used for adjusting whiteness, and an antistatic agent, a heat stabilizer, an antioxidant, an ultraviolet absorber, An additive such as a light stabilizer may be blended.

As the foaming agent to be blended in the foamed resin layer,
Known resin foaming agents can be used, for example, propane, butane, hydrocarbon gas such as pentane, azodicarbonamide, dinitropentamethylenetetramine, azodicarbonamide, dinitropentamethylenetetramine, azodiisobutyronitrile, sodium bicarbonate, sodium carbonate and the like. No. The expansion ratio is preferably about 1.1 to 2.0.

The present invention is not particularly limited except that the plurality of resin layers are extruded with a die. For example, when forming a foamed resin layer and a non-foamed resin layer one by one, a resin for a non-foamed resin layer containing no foaming agent is melt-extruded from a first die onto a cooling roll to form a non-foamed resin layer. Guiding the non-foamed resin layer to a nip between a pressure roll and a cooling roll, and separately guiding a paper base material to the nip along the pressure roll, thereby forming a paper base and a non-foamed resin layer of the nip. A resin layer for a foamed resin layer having a foaming agent is melt-extruded from the second die in between, whereby a resin layer can be formed on a paper base in the order of a foamed resin layer and a non-foamed resin layer.

The thickness of the support consisting of the paper base and the resin layer is
The range of 20 to 350 μm is preferred. The thickness of the support is 2
When it is less than 0 μm, not only the mechanical strength of the obtained receiving sheet becomes insufficient, but also its hardness and repulsion against deformation become insufficient, and the curling of the receiving sheet generated at the time of printing cannot be sufficiently prevented. In some cases. On the other hand, when the thickness exceeds 350 μm, the thickness of the obtained receiving sheet may be excessive. With a printer of a given volume, there is a limit to the receiving sheet storage volume,
An increase in the thickness of the receiving sheet naturally causes a decrease in the number of receiving sheets contained in the printer. In this case, in order to accommodate a predetermined number of receiving sheets, the volume of the printer must be increased, and it is difficult to make the printer compact. The thickness of the foamed resin layer is 5 to 100 μm.
m is preferable, and the thickness of the non-foamed resin layer is 2 to 2.
It is preferably about 30 μm.

In the receiving sheet of the present invention, a thermal transfer receiving layer is formed on the resin layer thus obtained. In the case of a sublimation transfer receiving sheet, a receiving layer is provided to receive the dye of the ink ribbon. The receiving layer is a layer containing a resin having a high dye-dyeing property as a main component, and appropriately adding a cross-linking agent, an anti-fusion agent, an ultraviolet absorber, and the like.
As the resin having a high dye-dyeing property, a cellulose resin, a polyvinyl acetal resin, a polyester resin, or the like is used. Further, a crosslinking agent is an isocyanate compound or an epoxy compound, etc .; A molding agent or the like is used. It is desirable that these receiving layer components cause a crosslinking reaction via a crosslinking agent. The coating amount of the receiving layer is 0.1
The range is preferably from ^{2 to} 20.0 g / m ² .

The back surface of the support is preferably coated with a water-resistant, thermoplastic resin such as a polyolefin resin by coating or by laminating, since curling due to moisture absorption of the paper substrate is preferably prevented. The polyolefin resin is selected from homopolymers of ethylene, α-olefins, for example, propylene, and at least two copolymers of the olefin, and two or more of these various polymers can be used in combination. is there. In particular, when the polyolefin resin layer is formed on the back surface of the support by extrusion using a die, the curl can be extremely stabilized, which is particularly preferable.

In the receiving sheet of the present invention, on the back surface (the side opposite to the receiving layer), the running performance is improved, static electricity is prevented, the receiving layer is prevented from being damaged due to mutual rubbing between the receiving sheets, and the printed receiving sheet is overlaid. When set aside, a back coating layer may be formed for the purpose of preventing the transfer of the dye from the receiving layer to the back surface of the receiving sheet in contact with and adjacent to the receiving layer. The back coating layer contains a resin which is effective as an adhesive, and this resin is also effective for the running property of the receiving sheet and for preventing the receiving layer surface from being damaged. As such a resin, an acrylic resin, an epoxy resin, a polyester resin, a phenol resin, an alkyd resin, a urethane resin, a melamine resin, and the like, and a reaction cured product of these resins can be used.

Various conductive agents can be added to the back coating layer for antistatic treatment. It is desirable to use a cationic polymer as the conductive agent. As the cationic polymer, generally, polyethyleneimine, an acrylic polymer containing a cationic monomer, a cation-modified acrylamide polymer, a cationic starch and the like can be used. The coating amount of the back coating layer is 0.3
It is desirably in the range of １５15 g / m ² . 0.3
If it is less than g / m ² , it may not be possible to sufficiently prevent damage to the receiving layer when the receiving layer and the back surface rub against each other. If it exceeds 15 g / m ² , the effect is saturated and uneconomical.

Each coating layer such as the receiving layer and the back coating layer in the present invention can be formed by coating and drying using a known coater such as a blade coater, an air knife coater and a gate roll coater.

[0023]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which, of course, are not intended to limit the present invention. In the examples, "parts" and "%" all indicate "parts by weight" and "% by weight".

Example ^On a base paper of 150 g / m ² in U.S.P., the components shown in Table 1 below were used, and a foamed resin layer and a non-foamed resin layer were formed on the front side so as to have the thickness shown in Table 2 below. , A non-foamed resin was provided by using a die, thereby obtaining five types of supports.

[0025]

[Table 1]

[0026]

[Table 2]

On the surface layer side of the obtained support, the following coating liquid for a receiving layer was applied so as to have a solid content of 8 g / m ² and dried (120 ° C., 1 minute) to form a receiving layer. Formed. Further, the following coating liquid for a back coating layer was applied at 1.5 g / m ² on the side opposite to the receiving layer and dried to obtain a back coating layer. In addition, this sheet
Zero sheets were stacked and crosslinking of the isocyanate was advanced in an oven at 60 ° C. to obtain a receiving sheet.

[Coating Liquid for Receptive Layer] Polyester resin (trade name: Byron 200, manufactured by Toyobo Co., Ltd.) 100 parts Silicone oil (trade name: KF393, manufactured by Shin-Etsu Silicon Co., Ltd.) 3 parts Isocyanate (trade name: Takenate D-140N, Takeda Pharmaceutical Co., Ltd.) 5 parts toluene 300 parts

“Coating liquid for back coating layer” Acrylic ester copolymer (trademark: Primal WL-81, manufactured by Rohm and Haas) 100 parts Epoxy resin (trademark: Epocoat DX-225, manufactured by Shell Chemical Company) 5 parts Conductive agent (trademark: Saftomer ST1000, manufactured by Mitsubishi Yuka Co., Ltd.) 50 parts Denatured ethanol 1420 parts

Evaluation The receiving sheet obtained in each of the above Examples and Comparative Examples was measured by the following method, and the results obtained are shown in Table 3.

[Image Uniformity] Each of three yellow, magenta, and cyan ink sheets each having an ink layer containing a sublimable dye together with a binder provided on a 6-μm-thick polyester film is brought into contact with a receptor sheet to obtain a commercially available image. Using a thermal transfer video printer (trade name: VY-50, manufactured by Hitachi, Ltd.), a predetermined image is thermally transferred to a receiving sheet by stepwise heating with a thermal head, and a halftone single color and color superimposed image of each color is obtained. Was printed. With respect to the recorded image transferred on the receiving sheet, the reflection density was measured for each applied energy using a Macbeth reflection densitometer RD-914 (trademark), and the optical density (black) was 1.0.
Was visually observed for the uniformity of the recorded image of the gradation portion corresponding to the presence or absence of shading unevenness and the presence of white spots. In the above, the evaluation results were rated 5 for excellent, 4 for good, 3 for normal, 2 for slightly defective, and 1 for markedly defective.

[Print Curl Measuring Method] After the sample was allowed to stand at 20 ° C. and 65% for 5 hours, square curls were measured, and the average value was used as an index as the curl of the receiving sheet.

[0033]

[Table 3]

[0034]

According to the present invention, there is provided a low-cost thermal transfer receiving sheet which has excellent printing suitability, hardly generates curl, has good surface gloss, and is suitable for various thermal printers. However, it greatly contributes to the industry.

Claims (3)

[Claims] In a thermal transfer receiving sheet having a support and a thermal transfer receiving layer, a plurality of resin layers in which at least one layer of the support is a foamed resin layer on a paper base and the upper layer is a non-foamed resin layer, A thermal transfer receiving sheet, which is formed by extruding using a die, and wherein a receiving layer is provided on the resin layer. 2. The thermal transfer receiving sheet according to claim 1, wherein both the foamed resin layer and the non-foamed resin layer are polyolefin resin layers. 3. The thermal transfer receiving sheet according to claim 1, wherein a polyolefin layer is formed by extrusion using a die on the opposite side of the receiving layer.